In European regulations, an adaptive front lighting system (AFS) has been specified. The AFS changes a light distribution pattern of a headlight during traveling in response to change in movement of a vehicle or change in environment outside the vehicle. For example, a headlight equipped with an AFS moves a light distribution in a left-right direction to ensure a wide field of view including a point of gaze of a driver who is traveling in a curve. The headlight equipped with the AFS allows the driver to quickly find obstacles, such as persons, animals, or parked vehicles. Thus, the driver can take evasive action with respect to an obstacle or the like more safely.
When a person, baggage, or the like is placed on a seat of a vehicle, the vehicle tilts in a front-back direction. Also, when the vehicle accelerates or decelerates, the vehicle tilts in the front-back direction. This shifts the light distribution of the headlight in an up-down direction. This causes the problem of dazzling an oncoming vehicle. “Dazzling” refers to confusing a person's vision. Against this problem, there is known an auto-leveling function of moving an optical axis of a light distribution of a headlight in an up-down direction.
A headlight equipped with an AFS capable of moving a light distribution in a left-right direction or an up-down direction can improve ensuring of the field of view of a driver and reduce dazzling of an oncoming vehicle, thereby contributing traffic safety. From these, there is a demand for a headlight that changes a light distribution pattern by moving a light distribution in a left-right direction or an up-down direction.
Patent Literature 1 discloses a drive mechanism that linearly moves a lens in a direction of an optical axis and a direction of an axis perpendicular to the optical axis. “Linearly moves” refers to causing it to move linearly.